Prodrugs of fumarates and their use in treating various diseases

ABSTRACT

The present invention provides compounds of formula (I), 
     
       
         
         
             
             
         
       
     
     wherein:
         R 1  is unsubstituted C 1 -C 6  alkyl;   L a  is substituted or unsubstituted C 1 -C 6  alkyl linker, substituted or unsubstituted C 3 -C 10  carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S; and   R 2  and R 3  are each, independently, H, substituted or unsubstituted C 1 -C 6  alkyl, or substituted or unsubstituted C 6 -C 10  aryl;   or alternatively, R 2  and R 3 , together with the nitrogen atom to which they are attached, form a substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S or a substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.       

     The invention also provides pharmaceutical compositions and methods for treating neurological diseases, such as multiple sclerosis.

RELATED APPLICATION

This application is a continuation of U.S. application Ser. No. 14/180,687, filed Feb. 14, 2014 which claims the benefit of U.S. Provisional Application No. 61/782,445, filed on Mar. 14, 2013. The entire teachings of the above applications are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to various prodrugs of monomethyl fumarate. In particular, the present invention relates to derivatives of monomethyl fumarate which offer improved properties relative to dimethyl fumarate. The invention also relates to methods of treating various diseases.

BACKGROUND OF THE INVENTION

Fumaric acid esters (FAEs) are approved in Germany for the treatment of psoriasis, are being evaluated in the United States for the treatment of psoriasis and multiple sclerosis, and have been proposed for use in treating a wide range of immunological, autoimmune, and inflammatory diseases and conditions.

FAEs and other fumaric acid derivatives have been proposed for use in treating a wide-variety of diseases and conditions involving immunological, autoimmune, and/or inflammatory processes including psoriasis (Joshi and Strebel, WO 1999/49858; U.S. Pat. No. 6,277,882; Mrowietz and Asadullah, Trends Mol Med 2005, 111(1), 43-48; and Yazdi and Mrowietz, Clinics Dermatology 2008, 26, 522-526); asthma and chronic obstructive pulmonary diseases (Joshi et al., WO 2005/023241 and US 2007/0027076); cardiac insufficiency including left ventricular insufficiency, myocardial infarction and angina pectoris (Joshi et al., WO 2005/023241; Joshi et al., US 2007/0027076); mitochondrial and neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, Huntington's disease, retinopathia pigmentosa and mitochondrial encephalomyopathy (Joshi and Strebel, WO 2002/055063, US 2006/0205659, U.S. Pat. No. 6,509,376, U.S. Pat. No. 6,858,750, and U.S. Pat. No. 7,157,423); transplantation (Joshi and Strebel, WO 2002/055063, US 2006/0205659, U.S. Pat. No. 6,359,003, U.S. Pat. No. 6,509,376, and U.S. Pat. No. 7,157,423; and Lehmann et al., Arch Dermatol Res 2002, 294, 399-404); autoimmune diseases (Joshi and Strebel, WO 2002/055063, U.S. Pat. No. 6,509,376, U.S. Pat. No. 7,157,423, and US 2006/0205659) including multiple sclerosis (MS) (Joshi and Strebel, WO 1998/52549 and U.S. Pat. No. 6,436,992; Went and Lieberburg, US 2008/0089896; Schimrigk et al., Eur J Neurology 2006, 13, 604-610; and Schilling et al., Clin Experimental Immunology 2006, 145, 101-107); ischemia and reperfusion injury (Joshi et al., US 2007/0027076); AGE-induced genome damage (Heidland, WO 2005/027899); inflammatory bowel diseases such as Crohn's disease and ulcerative colitis; arthritis; and others (Nilsson et al., WO 2006/037342 and Nilsson and Muller, WO 2007/042034).

FUMADERM®, an enteric coated tablet containing a salt mixture of monoethyl fumarate and dimethyl fumarate (DMF) which is rapidly hydrolyzed to monomethyl fumarate, regarded as the main bioactive metabolite, was approved in Germany in 1994 for the treatment of psoriasis. FUMADERM® is dosed TID with 1-2 grams/day administered for the treatment of psoriasis. FUMADERM® exhibits a high degree of interpatient variability with respect to drug absorption and food strongly reduces bioavailability. Absorption is thought to occur in the small intestine with peak levels achieved 5-6 hours after oral administration. Significant side effects occur in 70-90% of patients (Brewer and Rogers, Clin Expt'l Dermatology 2007, 32, 246-49; and Hoefnagel et al., Br J Dermatology 2003, 149, 363-369). Side effects of current FAE therapy include gastrointestinal upset including nausea, vomiting, diarrhea and/or transient flushing of the skin.

Multiple sclerosis (MS) is an autoimmune disease with the autoimmune activity directed against central nervous system (CNS) antigens. The disease is characterized by inflammation in parts of the CNS, leading to the loss of the myelin sheathing around neuronal axons (gradual demyelination), axonal loss, and the eventual death of neurons, oligodendrocytes and glial cells.

Dimethyl fumarate (DMF) is the active component of the experimental therapeutic, BG-12, studied for the treatment of relapsing-remitting MS (RRMS). In a Phase IIb RRMS study, BG-12 significantly reduced gadolinium-enhancing brain lesions. In preclinical studies, DMF administration has been shown to inhibit CNS inflammation in murine and rat EAE. It has also been found that DMF can inhibit astrogliosis and microglial activations associated with EAE. See, e.g., US Published Application No. 2012/0165404.

There are four major clinical types of MS: 1) relapsing-remitting MS (RRMS), characterized by clearly defined relapses with full recovery or with sequelae and residual deficit upon recovery; periods between disease relapses characterized by a lack of disease progression; 2) secondary progressive MS (SPMS), characterized by initial relapsing remitting course followed by progression with or without occasional relapses, minor remissions, and plateaus; 3) primary progressive MS (PPMS), characterized by disease progression from onset with occasional plateaus and temporary minor improvements allowed; and 4) progressive relapsing MS (PRMS), characterized by progressive disease onset, with clear acute relapses, with or without full recovery; periods between relapses characterized by continuing progression.

Clinically, the illness most often presents as a relapsing-remitting disease and, to a lesser extent, as steady progression of neurological disability. Relapsing-remitting MS (RRMS) presents in the form of recurrent attacks of focal or multifocal neurologic dysfunction. Attacks may occur, remit, and recur, seemingly randomly over many years. Remission is often incomplete and as one attack follows another, a stepwise downward progression ensues with increasing permanent neurological deficit. The usual course of RRMS is characterized by repeated relapses associated, for the majority of patients, with the eventual onset of disease progression. The subsequent course of the disease is unpredictable, although most patients with a relapsing-remitting disease will eventually develop secondary progressive disease. In the relapsing-remitting phase, relapses alternate with periods of clinical inactivity and may or may not be marked by sequelae depending on the presence of neurological deficits between episodes. Periods between relapses during the relapsing-remitting phase are clinically stable. On the other hand, patients with progressive MS exhibit a steady increase in deficits, as defined above and either from onset or after a period of episodes, but this designation does not preclude the further occurrence of new relapses.

Notwithstanding the above, dimethyl fumarate is also associated with significant drawbacks.

For example, dimethyl fumarate is known to cause side effects upon oral administration, such as flushing and gastrointestinal events including, nausea, diarrhea, and/or upper abdominal pain in subjects. See, e.g., Gold et al., N. Eng. J. Med., 2012, 367(12), 1098-1107. Dimethyl fumarate is dosed BID or TID with a total daily dose of about 480 mg to about 1 gram or more.

Further, in the use of a drug for long-term therapy it is desirable that the drug be formulated so that it is suitable for once- or twice-daily administration to aid patient compliance. A dosing frequency of once-daily or less is even more desirable.

Another problem with long-term therapy is the requirement of determining an optimum dose which can be tolerated by the patient. If such a dose is not determined this can lead to a diminution in the effectiveness of the drug being administered.

Accordingly, it is an object of the present invention to provide compounds and/or compositions which are suitable for long-term administration.

It is a further object of the present invention to provide the use of a pharmaceutical active agent in a manner which enables one to achieve a tolerable steady state level for the drug in a subject being treated therewith.

Because of the disadvantages of dimethyl fumarate described above, there continues to be a need to decrease the dosing frequency, reduce side-effects and/or improve the physicochemical properties associated with DMF. There remains, therefore, a real need in the treatment of neurological diseases, such as MS, for a product which retains the pharmacological advantages of DMF but overcomes its flaws in formulation and/or adverse effects upon administration. The present invention addresses these needs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the hydrolysis of Compound 16 at pH 7.9, 25° C., showing vinylic region, as observed by NMR over 90 minutes.

FIG. 2 depicts the hydrolysis of Compound 16 at pH 7.9, 25° C., showing vinylic region, as observed by NMR over 19 hours.

FIG. 3 depicts the hydrolysis of Compound 16 at pH 7.9, 25° C., showing aliphatic region, as observed by NMR over 19 hours.

FIG. 4 depicts the hydrolysis of Reference Compound A at pH 7.9, 37° C., showing vinylic region, as observed by NMR over 15 hours.

FIG. 5 depicts the hydrolysis of Reference Compound A at pH 7.9, 37° C., showing aliphatic region, as observed by NMR over 15 hours.

SUMMARY OF THE INVENTION

This invention is directed to the surprising and unexpected discovery of novel prodrugs and related methods useful in the treatment of neurological diseases. The methods and compositions described herein comprise one or more prodrugs (e.g., aminoalkyl prodrugs) of monomethyl fumarate (MMF). The methods and compositions provide for a therapeutically effective amount of an active moiety in a subject for a time period of at least about 8 hours to at least about 24 hours.

More specifically, the compounds of the invention can be converted in vivo, upon oral administration, to monomethyl fumarate. Upon conversion, the active moiety (i.e., monomethyl fumarate) is effective in treating subjects suffering from a neurological disease.

The present invention provides, in part, a compound of Formula (I), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof:

wherein:

R₁ is unsubstituted C₁-C₆ alkyl;

L_(a) is substituted or unsubstituted C₁-C₆ alkyl linker, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S; and

R₂ and R₃ are each, independently, H, substituted or unsubstituted C₁-C₆ alkyl, substituted or unsubstituted C₂-C₆ alkenyl, substituted or unsubstituted C₂-C₆ alkynyl, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S;

or alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S or a substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.

The present invention also provides pharmaceutical compositions comprising one or more compounds of any of the formulae described herein and one or more pharmaceutically acceptable carriers.

The present invention also provides methods of treating a neurological disease by administering to a subject in need thereof, a therapeutically effective amount of a compound of any of the formulae described herein, or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof, such that the disease is treated.

The present invention also provides methods of treating multiple sclerosis by administering to a subject in need thereof, a therapeutically effective amount of a compound of any of the formulae described herein, or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof, such that the multiple sclerosis is treated.

The present invention also provides methods of treating relapsing-remitting multiple sclerosis (RRMS) by administering to a subject in need thereof, a therapeutically effective amount of a compound of any of the formulae described herein, or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof, such that the multiple sclerosis is treated.

The present invention also provides methods of treating secondary progressive multiple sclerosis (SPMS) by administering to a subject in need thereof, a therapeutically effective amount of a compound of any of the formulae described herein, or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof, such that the multiple sclerosis is treated.

The present invention also provides methods of treating primary progressive multiple sclerosis (PPMS) by administering to a subject in need thereof, a therapeutically effective amount of a compound of any of the formulae described herein, or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof, such that the multiple sclerosis is treated.

The present invention also provides methods of treating progressive relapsing multiple sclerosis (PRMS) by administering to a subject in need thereof, a therapeutically effective amount of a compound of any of the formulae described herein, or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof, such that the multiple sclerosis is treated.

The present invention also provides methods of treating Alzheimer's disease by administering to a subject in need thereof, a therapeutically effective amount of a compound of any of the formulae described herein, or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof, such that the Alzheimer's disease is treated.

The present invention also provides methods of treating cerebral palsy by administering to a subject in need thereof, a therapeutically effective amount of a compound of any of the formulae described herein, or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof, such that the cerebral palsy is treated.

The present invention also provides compounds and compositions that enable improved oral, controlled- or sustained-release formulations. Specifically, dimethyl fumarate is administered twice or three times daily for the treatment of relapsing-remitting multiple sclerosis. In contrast, the compounds and compositions of the present invention may enable formulations with a modified duration of therapeutic efficacy for reducing relapse rates in subjects with multiple sclerosis. For example, the present compounds and compositions provide therapeutically effective amounts of monomethyl fumarate in subjects for at least about 8 hours, at least about 12 hours, at least about 16 hours, at least about 20 hours or at least about 24 hours.

The present invention also provides compounds, compositions and methods which may result in decreased side effects upon administration to a subject relative to dimethyl fumarate. For example, gastric irritation and flushing are known side effects of oral administration of dimethyl fumarate in some subjects. The compounds, compositions and methods of the present invention can be utilized in subjects that have experienced or are at risk of developing such side effects.

The present invention also provides for compounds and compositions which exhibit improved physical stability relative to dimethyl fumarate. Specifically, dimethyl fumarate is known in the art to undergo sublimation at ambient and elevated temperature conditions. The compounds of the invention possess greater physical stability than dimethyl fumarate under controlled conditions of temperature and relative humidity. Specifically, in one embodiment, the compounds of the formulae described herein exhibit decreased sublimation relative to dimethyl fumarate.

Further, dimethyl fumarate is also known to be a contact irritant. See e.g., Material Safety Data Sheet for DMF. In one embodiment, the compounds of the present invention exhibit reduced contact irritation relative to dimethyl fumarate. For example, the compounds of the formulae described herein exhibit reduced contact irritation relative to dimethyl fumarate.

The present invention also provides for compounds and compositions which exhibit decreased food effect relative to dimethyl fumarate. The bioavailability of dimethyl fumarate is known in the art to be reduced when administered with food. Specifically, in one embodiment, the compounds of the formulae described herein exhibit decreased food effect relative to dimethyl fumarate.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In the specification, the singular forms also include the plural unless the context clearly dictates otherwise. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. All publications, patent applications, patents and other references mentioned herein are incorporated by reference. The references cited herein are not admitted to be prior art to the claimed invention. In the case of conflict, the present specification, including definitions, will control. In addition, the materials, methods and examples are illustrative only and are not intended to be limiting.

Other features and advantages of the invention will be apparent from the following detailed description and claims.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides novel compounds and methods of treating a neurological disease by administering a compound of Formula (I), (Ia), (Ib), (II) or (III), synthetic methods for making a compound of Formula (I), (Ia), (Ib), (II) or (III), and pharmaceutical compositions containing a compound of Formula (I), (Ia), (Ib), (II) or (III).

The present invention also provides compounds and methods for the treatment of psoriasis by administering to a subject in need thereof, a therapeutically effective amount of a compound of Formula (I), (Ia), (Ib), (II) or (III), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof.

The present invention provides, in part, methods for the treatment of a neurological disease by administering to a subject in need thereof, a therapeutically effective amount of a compound of Formula (I), (Ia), (Ib), (II) or (III), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof. The neurological disease can be multiple sclerosis. The present invention further provides the use of a compound of Formula (I), (Ia), (Ib), (II) or (III), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof, for the preparation of a medicament useful for the treatment of a neurological disease.

According to the present invention, a neurological disease is a disorder of the brain, spinal cord or nerves in a subject. In one embodiment, the neurological disease is characterized by demyelination, or degeneration of the myelin sheath, of the central nervous system. The myelin sheath facilitates the transmission of nerve impulses through a nerve fiber or axon. In another embodiment, the neurological disease is selected from the group consisting of multiple sclerosis, Alzheimer's disease, cerebral palsy, spinal cord injury, Amyotrophic lateral sclerosis (ALS), stroke, and Huntington's disease, Parkinson's disease, optic neuritis, Devic disease, transverse myelitis, acute disseminated encephalomyelitis, adrenoleukodystrophy and adrenomyeloneuropathy, acute inflammatory demyelinating polyneuropathy (AIDP), chronic inflammatory demyelinating polyneuropathy (CIDP), acute transverse myelitis, progressive multifocal leucoencephalopathy (PML), acute disseminated encephalomyelitis (ADEM) and other hereditary disorders, such as leukodystrophies, Leber's optic atrophy, and Charcot-Marie-Tooth disease. In some embodiments, the neurological disorder is an auto-immune disease. In one embodiment, the neurological disease is multiple sclerosis. In another embodiment, the neurological disease is stroke. In another embodiment, the neurological disease is Alzheimer's disease. In another embodiment, the neurological disease is cerebral palsy. In another embodiment, the neurological disease is spinal cord injury. In another embodiment, the neurological disease is ALS. In another embodiment, the neurological disease is Huntington's disease. See, e.g., U.S. Pat. No. 8,007,826, WO2005/099701 and WO2004/082684, which are incorporated by reference in their entireties.

In a further embodiment, the present invention provides methods for the treatment of a disease or a symptom of a disease described herein by administering to a subject in need thereof, a therapeutically effective amount of a compound of Formula (I), (Ia), (Ib), (II) or (III), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof. The present invention further provides the use of a compound of Formula (I), (Ia), (Ib), (II) or (III), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof, for the preparation of a medicament useful for the treatment of a disease or a symptom of a disease described herein.

In another embodiment, the present invention provides a compound of Formula (I), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof, or a method for the treatment of a neurological disease by administering to a subject in need thereof, a therapeutically effective amount of a compound of Formula (I), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof:

wherein:

R₁ is unsubstituted C₁-C₆ alkyl;

L_(a) is substituted or unsubstituted C₁-C₆ alkyl linker, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S; and

R₂ and R₃ are each, independently, H, substituted or unsubstituted C₁-C₆ alkyl, substituted or unsubstituted C₂-C₆ alkenyl, substituted or unsubstituted C₂-C₆ alkynyl, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S;

or alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S or a substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.

For example, the neurological disease is multiple sclerosis.

For example, the neurological disease is relapsing-remitting multiple sclerosis (RRMS).

For example, the compound of Formula (I) is a compound listed in Table 1 herein.

For example, in the compound of Formula (I), R₁ is methyl.

For example, in the compound of Formula (I), R₁ is ethyl.

For example, in the compound of Formula (I), L_(a) is substituted or unsubstituted C₁-C₆ alkyl linker.

For example, in the compound of Formula (I), L_(a) is substituted or unsubstituted C₁-C₃ alkyl linker.

For example, in the compound of Formula (I), L_(a) is substituted or unsubstituted C₂ alkyl linker.

For example, in the compound of Formula (I), L_(a) is methyl substituted or unsubstituted C₂ alkyl linker.

For example, in the compound of Formula (I), L_(a) is di-methyl substituted or unsubstituted C₂ alkyl linker.

For example, in the compound of Formula (I), L_(a) is methyl or di-methyl substituted C₂ alkyl linker.

For example, in the compound of Formula (I), L_(a) is unsubstituted C₂ alkyl linker.

For example, in the compound of Formula (I), R₂ is substituted or unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (I), R₂ is unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (I), R₂ is unsubstituted C₁-C₃ alkyl.

For example, in the compound of Formula (I), R₂ is unsubstituted C₁-C₂ alkyl.

For example, in the compound of Formula (I), R₂ is C(O)OR_(a)-substitutedC₁-C₆ alkyl, wherein R_(a) is H or unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (I), R₂ is S(O)(O)R_(b)-substitutedC₁-C₆ alkyl, wherein R_(b) is unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (I), R₃ is H.

For example, in the compound of Formula (I), R₃ is substituted or unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (I), R₃ is unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (I), R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or a substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.

For example, in the compound of Formula (I), R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.

For example, in the compound of Formula (I), R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted pyrrolidinyl, imidazolidinyl, pyrazolidinyl, oxazolidinyl, isoxazolidinyl, triazolidinyl, tetrahydrofuranyl, piperidinyl, piperazinyl, or morpholinyl ring.

For example, in the compound of Formula (I), R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted piperidinyl ring.

For example, in the compound of Formula (I), R₂ and R₃, together with the nitrogen atom to which they are attached, form an unsubstituted piperidinyl ring.

For example, in the compound of Formula (I), R₂ and R₃, together with the nitrogen atom to which they are attached, form a halogen substituted piperidinyl ring.

For example, in the compound of Formula (I), R₂ and R₃, together with the nitrogen atom to which they are attached, form a 4-halogen substituted piperidinyl ring.

For example, in the compound of Formula (I), R₂ and R₃, together with the nitrogen atom to which they are attached, form an unsubstituted morpholinyl ring.

For example, in the compound of Formula (I), R₂ and R₃, together with the nitrogen atom to which they are attached, form an unsubstituted pyrrolidinyl ring.

For example, in the compound of Formula (I), R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted heteroaryl comprising one or two 5 or 6-member rings and 1-4 heteroatoms selected from N, O and S.

For example, in the compound of Formula (I), R₂ is substituted or unsubstituted C₆-C₁₀ aryl.

For example, in the compound of Formula (I), R₂ is unsubstituted C₆-C₁₀ aryl.

For example, in the compound of Formula (I), R₂ is unsubstituted phenyl.

For example, in the compound of Formula (I), R₂ is unsubstituted benzyl.

In another embodiment, the present invention provides a compound of Formula (Ia), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof, or a method for the treatment of a neurological disease by administering to a subject in need thereof a therapeutically effective amount of a compound of Formula (Ia), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof:

wherein:

R₁ is unsubstituted C₁-C₆ alkyl;

L_(a) is substituted or unsubstituted C₁-C₆ alkyl linker, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S; and

R₂ is H, substituted or unsubstituted C₁-C₆ alkyl, substituted or unsubstituted C₂-C₆ alkenyl, substituted or unsubstituted C₂-C₆ alkynyl, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.

For example, the neurological disease is multiple sclerosis.

For example, the neurological disease is relapsing-remitting multiple sclerosis (RRMS).

For example, in the compound of Formula (Ia), R₁ is methyl.

For example, in the compound of Formula (Ia), R₁ is ethyl.

For example, in the compound of Formula (Ia), L_(a) is substituted or unsubstituted C₁-C₆ alkyl linker.

For example, in the compound of Formula (Ia), L_(a) is substituted or unsubstituted C₁-C₃ alkyl linker.

For example, in the compound of Formula (Ia), L_(a) is substituted or unsubstituted C₂ alkyl linker.

For example, in the compound of Formula (Ia), L_(a) is methyl substituted or unsubstituted C₂ alkyl linker.

For example, in the compound of Formula (Ia), L_(a) is di-methyl substituted or unsubstituted C₂ alkyl linker.

For example, in the compound of Formula (Ia), L_(a) is methyl or di-methyl substituted C₂ alkyl linker.

For example, in the compound of Formula (Ia), L_(a) is unsubstituted C₂ alkyl linker.

For example, in the compound of Formula (Ia), R₂ is substituted or unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (Ia), R₂ is unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (Ia), R₂ is methyl.

For example, in the compound of Formula (Ia), R₂ is unsubstituted C₁-C₃ alkyl.

For example, in the compound of Formula (Ia), R₂ is unsubstituted C₁-C₂ alkyl.

For example, in the compound of Formula (Ia), R₂ is C(O)OR_(a)-substitutedC₁-C₆ alkyl, wherein R_(a) is H or unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (Ia), R₂ is S(O)(O)R_(b)-substitutedC₁-C₆ alkyl, wherein R_(b) is unsubstituted C₁-C₆ alkyl.

In another embodiment, the present invention provides a compound of Formula (Ib), or a pharmaceutically acceptable polymorph, hydrate, solvate or co-crystal thereof, or a method for the treatment of a neurological disease by administering to a subject in need thereof a therapeutically effective amount of a compound of Formula (Ib), or a pharmaceutically acceptable polymorph, hydrate, solvate or co-crystal thereof:

A⁻ is a pharmaceutically acceptable anion;

R₁ is unsubstituted C₁-C₆ alkyl;

L_(a) is substituted or unsubstituted C₁-C₆ alkyl linker, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S;

R₃′ is substituted or unsubstituted C₁-C₆ alkyl; and

R₂ and R₃ are each, independently, H, substituted or unsubstituted C₁-C₆ alkyl, substituted or unsubstituted C₂-C₆ alkenyl, substituted or unsubstituted C₂-C₆ alkynyl, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S;

or alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or a substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.

For example, the neurological disease is multiple sclerosis.

For example, the neurological disease is relapsing-remitting multiple sclerosis (RRMS).

For example, in the compound of Formula (Ib), R₁ is methyl.

For example, in the compound of Formula (Ib), R₁ is ethyl.

For example, in the compound of Formula (Ib), L_(a) is substituted or unsubstituted C₁-C₆ alkyl linker.

For example, in the compound of Formula (Ib), L_(a) is substituted or unsubstituted C₁-C₃ alkyl linker.

For example, in the compound of Formula (Ib), L_(a) is substituted or unsubstituted C₂ alkyl linker.

For example, in the compound of Formula (Ib), L_(a) is methyl substituted or unsubstituted C₂ alkyl linker.

For example, in the compound of Formula (Ib), L_(a) is di-methyl substituted or unsubstituted C₂ alkyl linker.

For example, in the compound of Formula (Ib), L_(a) is methyl or di-methyl substituted C₂ alkyl linker.

For example, in the compound of Formula (Ib), L_(a) is unsubstituted C₂ alkyl linker.

For example, in the compound of Formula (Ib), R₂ is substituted or unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (Ib), R₂ is unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (Ib), R₂ is unsubstituted C₁-C₃ alkyl.

For example, in the compound of Formula (Ib), R₂ is unsubstituted C₁-C₂ alkyl.

For example, in the compound of Formula (Ib), R₂ is C(O)OR_(a)-substitutedC₁-C₆ alkyl, wherein R_(a) is H or unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (Ib), R₂ is S(O)(O)R_(b)-substitutedC₁-C₆ alkyl, wherein R_(b) is unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (Ib), R₃ is H.

For example, in the compound of Formula (Ib), R₃ is substituted or unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (Ib), R₃ is unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (Ib), R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or a substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.

For example, in the compound of Formula (Ib), R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.

For example, in the compound of Formula (Ib), R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted pyrrolidinyl, imidazolidinyl, pyrazolidinyl, oxazolidinyl, isoxazolidinyl, triazolidinyl, tetrahydrofuranyl, piperidinyl, piperazinyl, or morpholinyl ring.

For example, in the compound of Formula (Ib), R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted piperidinyl ring.

For example, in the compound of Formula (Ib), R₂ and R₃, together with the nitrogen atom to which they are attached, form an unsubstituted piperidinyl ring.

For example, in the compound of Formula (Ib), R₂ and R₃, together with the nitrogen atom to which they are attached, form a halogen substituted piperidinyl ring.

For example, in the compound of Formula (Ib), R₂ and R₃, together with the nitrogen atom to which they are attached, form a 4-halogen substituted piperidinyl ring.

For example, in the compound of Formula (Ib), R₂ and R₃, together with the nitrogen atom to which they are attached, form an unsubstituted morpholinyl ring.

For example, in the compound of Formula (Ib), R₂ and R₃, together with the nitrogen atom to which they are attached, form an unsubstituted pyrrolidinyl ring.

For example, in the compound of Formula (Ib), R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.

For example, in the compound of Formula (Ib), R₂ is substituted or unsubstituted C₆-C₁₀ aryl.

For example, in the compound of Formula (Ib), R₂ is unsubstituted C₆-C₁₀ aryl.

For example, in the compound of Formula (Ib), R₂ is unsubstituted phenyl.

For example, in the compound of Formula (Ib), R₂ is unsubstituted benzyl.

For example, in the compound of Formula (Ib), R₃′ is unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (Ib), R₃′ is unsubstituted C₁-C₃ alkyl.

For example, in the compound of Formula (Ib), R₃′ is methyl.

In one embodiment, the present invention provides a compound of Formula (II), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof, or a method for the treatment of a neurological disease by administering to a subject in need thereof a therapeutically effective amount of a compound of Formula (II), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof:

wherein:

R₁ is unsubstituted C₁-C₆ alkyl;

R₄ and R₅ are each, independently, H, substituted or unsubstituted C₁-C₆ alkyl, substituted or unsubstituted C₂-C₆ alkenyl, substituted or unsubstituted C₂-C₆ alkynyl, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S;

R₆, R₇, R₈ and R₉ are each, independently, H, substituted or unsubstituted C₁-C₆ alkyl, substituted or unsubstituted C₂-C₆ alkenyl, substituted or unsubstituted C₂-C₆ alkynyl or C(O)OR_(a); and

R_(a) is H or substituted or unsubstituted C₁-C₆ alkyl.

For example, the neurological disease is multiple sclerosis.

For example, the neurological disease is relapsing-remitting multiple sclerosis (RRMS).

For example, in the compound of Formula (II), R₁ is methyl.

For example, in the compound of Formula (II), R₁ is ethyl.

For example, in the compound of Formula (II), R₄ is substituted or unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (II), R₄ is unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (II), R₄ is unsubstituted C₁-C₃ alkyl.

For example, in the compound of Formula (II), R₄ is unsubstituted C₁-C₂ alkyl.

For example, in the compound of Formula (II), R₄ is C(O)OR_(a)-substitutedC₁-C₆ alkyl, wherein R_(a) is H or unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (II), R₄ is S(O)(O)R_(b)-substitutedC₁-C₆ alkyl, wherein R_(b) is unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (II), R₅ is H.

For example, in the compound of Formula (II), R₅ is substituted or unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (II), R₅ is unsubstituted C₁-C₆ alkyl.

For example, in the compound of Formula (II), R₄ is substituted or unsubstituted C₆-C₁₀ aryl.

For example, in the compound of Formula (II), R₄ is unsubstituted C₆-C₁₀ aryl.

For example, in the compound of Formula (II), R₄ is unsubstituted phenyl.

For example, in the compound of Formula (II), R₄ is unsubstituted benzyl.

For example, in the compound of Formula (II), R₆, R₇, R₈ and R₉ are each H.

For example, in the compound of Formula (II), R₆ is substituted or unsubstituted C₁-C₆ alkyl and R₇, R₈ and R₉ are each H.

For example, in the compound of Formula (II), R₆ is unsubstituted C₁-C₆ alkyl and R₇, R₈ and R₉ are each H.

For example, in the compound of Formula (II), R₈ is substituted or unsubstituted C₁-C₆ alkyl and R₆, R₇ and R₉ are each H.

For example, in the compound of Formula (II), R₈ is unsubstituted C₁-C₆ alkyl and R₆, R₇ and R₉ are each H.

For example, in the compound of Formula (II), R₆ and R₈ are each, independently, substituted or unsubstituted C₁-C₆ alkyl and R₇ and R₉ are each H.

For example, in the compound of Formula (II), R₆ and R₈ are each, independently, unsubstituted C₁-C₆ alkyl and R₇ and R₉ are each H.

For example, in the compound of Formula (II), R₆ and R₇ are each, independently, substituted or unsubstituted C₁-C₆ alkyl and R₈ and R₉ are each H.

For example, in the compound of Formula (II), R₆ and R₇ are each, independently, unsubstituted C₁-C₆ alkyl and R₈ and R₉ are each H.

For example, in the compound of Formula (II), R₈ and R₉ are each, independently, substituted or unsubstituted C₁-C₆ alkyl and R₆ and R₇ are each H.

For example, in the compound of Formula (II), R₈ and R₉ are each, independently, unsubstituted C₁-C₆ alkyl and R₆ and R₇ are each H.

In one embodiment, the present invention provides a compound of Formula (III), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof, or a method for the treatment of a neurological disease by administering to a subject in need thereof a therapeutically effective amount of a compound of Formula (III), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof:

wherein:

R₁ is unsubstituted C₁-C₆ alkyl;

is selected from the group consisting of:

X is N, O, S or SO₂;

Z is C or N;

m is 0, 1, 2, or 3;

n is 1 or 2;

w is 0, 1, 2 or 3;

t is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10;

R₆, R₇, R₈ and R₉ are each, independently, H, substituted or unsubstituted C₁-C₆ alkyl, substituted or unsubstituted C₂-C₆ alkenyl, substituted or unsubstituted C₂-C₆ alkynyl or C(O)OR_(a); and

R_(a) is H or substituted or unsubstituted C₁-C₆ alkyl; and

each R₁₀ is, independently, H, halogen, substituted or unsubstituted C₁-C₆ alkyl, substituted or unsubstituted C₂-C₆ alkenyl, substituted or unsubstituted C₂-C₆ alkynyl, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S;

or, alternatively, two R₁₀'s attached to the same carbon atom, together with the carbon atom to which they are attached, form a carbonyl, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S;

or, alternatively, two R₁₀'s attached to different atoms, together with the atoms to which they are attached, form a substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.

For example, the neurological disease is multiple sclerosis.

For example, the neurological disease is relapsing-remitting multiple sclerosis (RRMS).

For example, in the compound of Formula (III), R₁ is methyl.

For example, in the compound of Formula (III), R₁ is ethyl.

For example, in the compound of Formula (III),

For example, in the compound of Formula (III),

For example, in the compound of Formula (III),

For example, in the compound of Formula (III),

For example, in the compound of Formula (III), R₆ is substituted or unsubstituted C₁-C₆ alkyl and R₇, R₈ and R₉ are each H.

For example, in the compound of Formula (III), R₆ is unsubstituted C₁-C₆ alkyl and R₇, R₈ and R₉ are each H.

For example, in the compound of Formula (III), R₈ is substituted or unsubstituted C₁-C₆ alkyl and R₆, R₇ and R₉ are each H.

For example, in the compound of Formula (III), R₈ is unsubstituted C₁-C₆ alkyl and R₆, R₇ and R₉ are each H.

For example, in the compound of Formula (III), R₆ and R₈ are each, independently, substituted or unsubstituted C₁-C₆ alkyl and R₇ and R₉ are each H.

For example, in the compound of Formula (III), R₆ and R₈ are each, independently, unsubstituted C₁-C₆ alkyl and R₇ and R₉ are each H.

For example, in the compound of Formula (III), R₆ and R₇ are each, independently, substituted or unsubstituted C₁-C₆ alkyl and R₈ and R₉ are each H.

For example, in the compound of Formula (III), R₆ and R₇ are each, independently, unsubstituted C₁-C₆ alkyl and R₈ and R₉ are each H.

For example, in the compound of Formula (III), R₈ and R₉ are each, independently, substituted or unsubstituted C₁-C₆ alkyl and R₆ and R₇ are each H.

For example, in the compound of Formula (III), R₈ and R₉ are each, independently, unsubstituted C₁-C₆ alkyl and R₆ and R₇ are each H.

For example, the compound is a compound listed in Table 1 herein.

Representative compounds of the present invention include compounds listed in Table 1.

TABLE 1

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20 A⁻ is a pharmaceutically acceptable anion.

The present invention also provides pharmaceutical compositions comprising one or more compounds of Formula (I), (Ia), (Ib), (II) or (III) and one or more pharmaceutically acceptable carriers.

In one embodiment, the pharmaceutical composition is a controlled release composition comprising a compound of Formula (I), (Ia), (Ib), (II) or (III) and one or more pharmaceutically acceptable carriers, wherein the controlled release composition provides a therapeutically effective amount of monomethyl fumarate to a subject. In another embodiment, the pharmaceutical composition is a controlled release composition comprising a compound of Formula (I), (Ia), (Ib), (II) or (III) and one or more pharmaceutically acceptable carriers, wherein the controlled release composition provides a therapeutically effective amount of monomethyl fumarate to a subject for at least about 8 hours to at least about 24 hours.

In another embodiment, the pharmaceutical composition is a controlled release composition comprising a compound of Formula (I), (Ia), (Ib), (II) or (III) and one or more pharmaceutically acceptable carriers, wherein the controlled release composition provides a therapeutically effective amount of monomethyl fumarate to a subject for at least about 8 hours, at least about 10 hours, at least about 12 hours, at least about 13 hours, at least about 14 hours, at least about 15 hours, at least about 16 hours, at least about 17 hours, at least about 18 hours, at least about 19 hours, at least about 20 hours, at least about 21 hours, at least about 22 hours, at least about 23 hours or at least about 24 hours or longer. For example, at least about 18 hours. For example, at least about 12 hours. For example, greater than 12 hours. For example, at least about 16 hours. For example, at least about 20 hours. For example, at least about 24 hours.

In another embodiment, a compound of Formula (I), (Ia), (Ib), (II) or (III) is efficiently converted to the active species, i.e., monomethyl fumarate, upon oral administration. For example, about 50 mole percent, about 55 mole percent, about 60 mole percent, about 65 mole percent, about 70 mole percent, about 75 mole percent, about 80 mole percent, about 85 mole percent, about 90 mole percent, or greater than 90 mole percent of the total dose of a compound of Formula (I), (Ia), (Ib), (II) or (III) administered is converted to monomethyl fumarate upon oral administration. In another embodiment, a compound of Formula (I), (Ia), (Ib), (II) or (III) is converted to the active species, i.e., monomethyl fumarate, upon oral administration more efficiently than dimethyl fumarate. In another embodiment, a compound of Formula (I), (Ia), (Ib), (II) or (III) is converted to the active species, i.e., monomethyl fumarate, upon oral administration more efficiently than one or more of the compounds described in U.S. Pat. No. 8,148,414. For example, a compound of Formula (I), (Ia), (Ib), (II) or (III) is essentially completely converted to the active species, i.e., monomethyl fumarate, upon oral administration. U.S. Pat. No. 8,148,414 is expressly incorporated by reference herein.

In another embodiment, any one of Compounds 1-20 is efficiently converted to the active species, i.e., monomethyl fumarate, upon oral administration. For example, about 50 percent, about 55 percent, about 60 percent, about 65 percent, about 70 percent, about 75 percent, about 80 percent, about 85 percent, about 90 percent, or greater than 90 percent of the total dose of any one of Compounds 1-20 administered is converted to monomethyl fumarate upon oral administration. In another embodiment, any one of Compounds 1-20 is converted to the active species, i.e., monomethyl fumarate, upon oral administration more efficiently than dimethyl fumarate. In another embodiment, any one of Compounds 1-20 is converted to the active species, i.e., monomethyl fumarate, upon oral administration more efficiently than one or more of the compounds described in U.S. Pat. No. 8,148,414. For example, any one of Compounds 1-20 is completely converted to the active species, i.e., monomethyl fumarate, upon oral administration.

For a drug to achieve its therapeutic effect, it is necessary to maintain the required level of blood or plasma concentration. Many drugs, including dimethyl fumarate, must be administered multiple times a day to maintain the required concentration. Furthermore, even with multiple administrations of such a drug per day, the blood or plasma concentrations of the active ingredient may still vary with time, i.e., at certain time points between administrations there are higher concentrations of the active ingredient than at other times. Thus, at certain time points of a 24-hour period, a patient may receive therapeutically effective amounts of the active ingredient, while at other time points the concentration of the active ingredient in the blood may fall below therapeutic levels. Additional problems with such drugs include that multiple dosing a day often adversely affects patient compliance with the treatment. Therefore, it is desirable to have a drug dosage form wherein the active ingredient is delivered in such a controlled manner that a constant or substantially constant level of blood or plasma concentration of the active ingredient can be achieved by one or at most two dosing per day. Accordingly, the present invention provides controlled-release formulations as described below. In general, such formulations are known to those skilled in the art or are available using conventional methods.

As used herein, “controlled-release” means a dosage form in which the release of the active agent is controlled or modified over a period of time. Controlled can mean, for example, sustained, delayed or pulsed-release at a particular time. For example, controlled-release can mean that the release of the active ingredient is extended for longer than it would be in an immediate-release dosage form, i.e., at least over several hours.

As used herein, “immediate-release” means a dosage form in which greater than or equal to about 75% of the active ingredient is released within two hours, or, more specifically, within one hour, of administration. Immediate-release or controlled-release may also be characterized by their dissolution profiles.

Formulations may also be characterized by their pharmacokinetic parameters. As used herein, “pharmacokinetic parameters” describe the in vivo characteristics of the active ingredient over time, including for example plasma concentration of the active ingredient. As used herein, “C_(max)” means the measured concentration of the active ingredient in the plasma at the point of maximum concentration. “T_(max)” refers to the time at which the concentration of the active ingredient in the plasma is the highest. “AUC” is the area under the curve of a graph of the concentration of the active ingredient (typically plasma concentration) vs. time, measured from one time to another.

The controlled-release formulations provided herein provide desirable properties and advantages. For example, the formulations can be administered once daily, which is particularly desirable for the subjects described herein. The formulation can provide many therapeutic benefits that are not achieved with corresponding shorter acting, or immediate-release preparations. For example, the formulation can maintain lower, more steady plasma peak values, for example, C_(max), so as to reduce the incidence and severity of possible side effects.

Sustained-release dosage forms release their active ingredient into the gastro-intestinal tract of a patient over a sustained period of time following administration of the dosage form to the patient. Particular dosage forms include: (a) those in which the active ingredient is embedded in a matrix from which it is released by diffusion or erosion; (b) those in which the active ingredient is present in a core which is coated with a release rate-controlling membrane; (c) those in which the active ingredient is present in a core provided with an outer coating impermeable to the active ingredient, the outer coating having an aperture (which may be drilled) for release of the active ingredient; (d) those in which the active ingredient is released through a semi-permeable membrane, allowing the drug to diffuse across the membrane or through liquid filled pores within the membrane; and (e) those in which the active ingredient is present as an ion exchange complex.

It will be apparent to those skilled in the art that some of the above means of achieving sustained-release may be combined, for example a matrix containing the active compound may be formed into a multiparticulate and/or coated with an impermeable coating provided with an aperture.

Pulsed-release formulations release the active compound after a sustained period of time following administration of the dosage form to the patient. The release may then be in the form of immediate- or sustained-release. This delay may be achieved by releasing the drug at particular points in the gastro-intestinal tract or by releasing drug after a pre-determined time. Pulsed-release formulations may be in the form of tablets or multiparticulates or a combination of both. Particular dosage forms include: (a) osmotic potential triggered release (see U.S. Pat. No. 3,952,741); (b) compression coated two layer tablets (see U.S. Pat. No. 5,464,633); (c) capsules containing an erodible plug (see U.S. Pat. No. 5,474,784); 4. sigmoidal releasing pellets (referred to in U.S. Pat. No. 5,112,621); and (d) formulations coated with or containing pH-dependent polymers including shellac, phthalate derivatives, polyacrylic acid derivatives and crotonic acid copolymers.

Dual release formulations can combine the active ingredient in immediate release form with additional active ingredient in controlled-release form. For example, a bilayer tablet can be formed with one layer containing immediate release active ingredient and the other layer containing the active ingredient embedded in a matrix from which it is released by diffusion or erosion. Alternatively, one or more immediate release beads can be combined with one or more beads which are coated with a release rate-controlling membrane in a capsule to give a dual release formulation. Sustained release formulations in which the active ingredient is present in a core provided with an outer coating impermeable to the active ingredient, the outer coating having an aperture (which may be drilled) for release of the active ingredient, can be coated with drug in immediate release form to give a dual release formulation. Dual release formulations can also combine drug in immediate release form with additional drug in pulsed release form. For example, a capsule containing an erodible plug could liberate drug initially and, after a predetermined period of time, release additional drug in immediate- or sustained-release form.

In some embodiments, the dosage forms to be used can be provided as controlled-release with respect to one or more active ingredients therein using, for example, hydroxypropylmethyl cellulose, other polymer matrices, gels, permeable membranes, osmotic systems, multilayer coatings, microparticles, liposomes, or microspheres or a combination thereof to provide the desired release profile in varying proportions. Suitable controlled-release formulations known to those of ordinary skill in the art, including those described herein, can be readily selected for use with the pharmaceutical compositions of the invention. Thus, single unit dosage forms suitable for oral administration, such as tablets, capsules, gelcaps, and caplets that are adapted for controlled-release are encompassed by the present invention.

Most controlled-release formulations are designed to initially release an amount of drug that promptly produces the desired therapeutic effect, and gradually and continually release of additional amounts of drug to maintain this level of therapeutic effect over an extended period of time. In order to maintain this constant level of drug in the body, the drug must be released from the dosage form at a rate that will replace the amount of drug being metabolized and excreted from the body.

Controlled-release of an active ingredient can be stimulated by various inducers, for example pH, temperature, enzymes, concentration, or other physiological conditions or compounds.

Powdered and granular formulations of a pharmaceutical preparation of the invention may be prepared using known methods. Such formulations may be administered directly to a subject, used, for example, to form tablets, to fill capsules, or to prepare an aqueous or oily suspension or solution by addition of an aqueous or oily vehicle thereto. Each of these formulations may further comprise one or more of a dispersing agent, wetting agent, suspending agent, and a preservative. Additional excipients, such as fillers, sweeteners, flavoring, or coloring agents, may also be included in these formulations.

A formulation of a pharmaceutical composition of the invention suitable for oral administration may be prepared or packaged in the form of a discrete solid dose unit including, but not limited to, a tablet, a hard or soft capsule, a cachet, a troche, or a lozenge, each containing a predetermined amount of the active ingredient. In one embodiment, a formulation of a pharmaceutical composition of the invention suitable for oral administration is coated with an enteric coat.

A tablet comprising the active ingredient may, for example, be made by compressing or molding the active ingredient, optionally with one or more additional ingredients. Compressed tablets may be prepared by compressing, in a suitable device, the active ingredient in a free flowing form such as a powder or granular preparation, optionally mixed with one or more of a binder, a lubricant, an excipient, a surface-active agent, and a dispersing agent. Molded tablets may be made by molding, in a suitable device, a mixture of the active ingredient, a pharmaceutically acceptable carrier, and at least sufficient liquid to moisten the mixture. Pharmaceutically acceptable excipients used in the manufacture of tablets include, but are not limited to, inert diluents, granulating and disintegrating agents, binding agents, and lubricating agents. Known dispersing agents include, but are not limited to, potato starch and sodium starch glycollate. Known surface-active agents include, but are not limited to, sodium lauryl sulphate and poloxamers. Known diluents include, but are not limited to, calcium carbonate, sodium carbonate, lactose, microcrystalline cellulose, calcium phosphate, calcium hydrogen phosphate, and sodium phosphate. Known granulating and disintegrating agents include, but are not limited to, corn starch and alginic acid. Known binding agents include, but are not limited to, gelatin, acacia, pre-gelatinized maize starch, polyvinylpyrrolidone, and hydroxypropyl methylcellulose. Known lubricating agents include, but are not limited to, magnesium stearate, stearic acid, silica, and talc.

Tablets may be non-coated or they may be coated using known methods to achieve delayed disintegration in the gastrointestinal tract of a subject, thereby providing sustained release and absorption of the active ingredient. By way of example, a material such as glyceryl monostearate or glyceryl distearate may be used to coat tablets. Further by way of example, tablets may be coated using methods described in U.S. Pat. Nos. 4,256,108; 4,160,452; and 4,265,874 to form osmotically-controlled release tablets, optionally, with laser drilling. Tablets may further comprise a sweetener, a flavoring agent, a coloring agent, a preservative, or some combination of these in order to provide for pharmaceutically elegant and palatable formulations.

Hard capsules comprising the active ingredient may be made using a physiologically degradable composition, such as gelatin or HPMC. Such hard capsules comprise the active ingredient, and may further comprise additional ingredients including, for example, an inert solid diluent such as calcium carbonate, calcium phosphate, or kaolin.

Soft gelatin capsules comprising the active ingredient may be made using a physiologically degradable composition, such as gelatin. Such soft capsules comprise the active ingredient, which may be mixed with water or an oil medium such as peanut oil, liquid paraffin, or olive oil.

As used herein, “alkyl”, “C₁, C₂, C₃, C₄, C₅ or C₆alkyl” or “C₁-C₆ alkyl” is intended to include C₁, C₂, C₃, C₄, C₅ or C₆ straight chain (linear) saturated aliphatic hydrocarbon groups and C₃, C₄, C₅ or C₆ branched saturated aliphatic hydrocarbon groups. For example, C₁-C₆ alkyl is intended to include C₁, C₂, C₃, C₄, C₅ and C₆ alkyl groups. Examples of alkyl include, moieties having from one to six carbon atoms, such as, but not limited to, methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, t-butyl, n-pentyl, s-pentyl or n-hexyl.

In certain embodiments, a straight chain or branched alkyl has six or fewer carbon atoms (e.g., C₁-C₆ for straight chain, C₃-C₆ for branched chain), and in another embodiment, a straight chain or branched alkyl has four or fewer carbon atoms.

As used herein, “alkyl linker” is intended to include C₁, C₂, C₃, C₄, C₅ or C₆ straight chain (linear) saturated aliphatic hydrocarbon groups and C₃, C₄, C₅ or C₆ branched saturated aliphatic hydrocarbon groups. For example, C₁-C₆ alkyl linker is intended to include C₁, C₂, C₃, C₄, C₅ and C₆alkyl linker groups. Examples of alkyl linker include, moieties having from one to six carbon atoms, such as, but not limited to, methyl (—CH₂—), ethyl (—CH₂CH₂—), n-propyl (—CH₂CH₂CH₂—), i-propyl (—CHCH₃CH₂—), n-butyl (—CH₂CH₂CH₂CH₂—), s-butyl (—CHCH₃CH₂CH₂—), i-butyl (—C(CH₃)₂CH₂—), n-pentyl (—CH₂CH₂CH₂CH₂CH₂—), s-pentyl (—CHCH₃CH₂CH₂CH₂—) or n-hexyl (—CH₂CH₂CH₂CH₂CH₂CH₂—). The term “substituted alkyl linker” refers to alkyl linkers having substituents replacing one or more hydrogen atoms on one or more carbons of the hydrocarbon backbone. Such substituents do not alter the sp3-hybridization of the carbon atom to which they are attached and include those listed below for “substituted alkyl.”

“Heteroalkyl” groups are alkyl groups, as defined above, that have an oxygen, nitrogen, sulfur or phosphorous atom replacing one or more hydrocarbon backbone carbon atoms.

As used herein, the term “cycloalkyl”, “C₃, C₄, C₅, C₆, C₇ or C₈ cycloalkyl” or “C₃-C₈ cycloalkyl” is intended to include hydrocarbon rings having from three to eight carbon atoms in their ring structure. In one embodiment, a cycloalkyl group has five or six carbons in the ring structure.

The term “substituted alkyl” refers to alkyl moieties having substituents replacing one or more hydrogen atoms on one or more carbons of the hydrocarbon backbone. Such substituents can include, for example, alkyl, alkenyl, alkynyl, halogen, hydroxyl, alkylcarbonyloxy, arylcarbonyloxy, alkoxycarbonyloxy, aryloxycarbonyloxy, carboxylate, alkylcarbonyl, arylcarbonyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, alkylthiocarbonyl, alkoxyl, phosphate, phosphonato, phosphinato, amino (including alkylamino, dialkylamino, arylamino, diarylamino and alkylarylamino), acylamino (including alkylcarbonylamino, arylcarbonylamino, carbamoyl and ureido), amidino, imino, sulfhydryl, alkylthio, arylthio, thiocarboxylate, sulfates, alkylsulfinyl, sulfonato, sulfamoyl, sulfonamido, nitro, trifluoromethyl, cyano, azido, heterocyclyl, alkylaryl, or an aromatic or heteroaromatic moiety. Cycloalkyls can be further substituted, e.g., with the substituents described above. An “alkylaryl” or an “aralkyl” moiety is an alkyl substituted with an aryl (e.g., phenylmethyl(benzyl)).

Unless the number of carbons is otherwise specified, “lower alkyl” includes an alkyl group, as defined above, having from one to six, or in another embodiment from one to four, carbon atoms in its backbone structure. “Lower alkenyl” and “lower alkynyl” have chain lengths of, for example, two to six or of two to four carbon atoms.

“Aryl” includes groups with aromaticity, including “conjugated”, or multicyclic, systems with at least one aromatic ring. Examples include phenyl, benzyl, naphthyl, etc.

“Heteroaryl” groups are aryl groups, as defined above, having from one to four heteroatoms in the ring structure, and may also be referred to as “aryl heterocycles” or “heteroaromatics”. As used herein, the term “heteroaryl” is intended to include a stable 5-, 6-, or 7-membered monocyclic or 7-, 8-, 9-, 10-, 11- or 12-membered bicyclic aromatic heterocyclic ring which consists of carbon atoms and one or more heteroatoms, e.g., 1 or 1-2 or 1-3 or 1-4 or 1-5 or 1-6 heteroatoms, independently selected from the group consisting of nitrogen, oxygen and sulfur. The nitrogen atom may be substituted or unsubstituted (i.e., N or NR wherein R is H or other substituents, as defined). The nitrogen and sulfur heteroatoms may optionally be oxidized (i.e., N→O and S(O)_(p), where p=1 or 2). It is to be noted that total number of S and O atoms in the heteroaryl is not more than 1.

Examples of heteroaryl groups include pyrrole, furan, thiophene, thiazole, isothiazole, imidazole, triazole, tetrazole, pyrazole, oxazole, isoxazole, pyridine, pyrazine, pyridazine, pyrimidine, and the like.

Furthermore, the terms “aryl” and “heteroaryl” include multicyclic aryl and heteroaryl groups, e.g., tricyclic, bicyclic, e.g., naphthalene, benzoxazole, benzodioxazole, benzothiazole, benzoimidazole, benzothiophene, methylenedioxyphenyl, quinoline, isoquinoline, naphthrydine, indole, benzofuran, purine, benzofuran, deazapurine, or indolizine.

In the case of multicyclic aromatic rings, only one of the rings needs to be aromatic (e.g., 2,3-dihydroindole), although all of the rings may be aromatic (e.g., quinoline). The second ring can also be fused or bridged.

The aryl or heteroaryl aromatic ring can be substituted at one or more ring positions with such substituents as described above, for example, alkyl, alkenyl, akynyl, halogen, hydroxyl, alkoxy, alkylcarbonyloxy, arylcarbonyloxy, alkoxycarbonyloxy, aryloxycarbonyloxy, carboxylate, alkylcarbonyl, alkylaminocarbonyl, aralkylaminocarbonyl, alkenylaminocarbonyl, alkylcarbonyl, arylcarbonyl, aralkylcarbonyl, alkenylcarbonyl, alkoxycarbonyl, aminocarbonyl, alkylthiocarbonyl, phosphate, phosphonato, phosphinato, amino (including alkylamino, dialkylamino, arylamino, diarylamino and alkylarylamino), acylamino (including alkylcarbonylamino, arylcarbonylamino, carbamoyl and ureido), amidino, imino, sulfhydryl, alkylthio, arylthio, thiocarboxylate, sulfates, alkylsulfinyl, sulfonato, sulfamoyl, sulfonamido, nitro, trifluoromethyl, cyano, azido, heterocyclyl, alkylaryl, or an aromatic or heteroaromatic moiety. Aryl groups can also be fused or bridged with alicyclic or heterocyclic rings, which are not aromatic so as to form a multicyclic system (e.g., tetralin, methylenedioxyphenyl).

As used herein, “carbocycle” or “carbocyclic ring” is intended to include any stable monocyclic, bicyclic or tricyclic ring having the specified number of carbons, any of which may be saturated, unsaturated, or aromatic. For example, a C₃-C₁₄ carbocycle is intended to include a monocyclic, bicyclic or tricyclic ring having 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14 carbon atoms. Examples of carbocycles include, but are not limited to, cyclopropyl, cyclobutyl, cyclobutenyl, cyclopentyl, cyclopentenyl, cyclohexyl, cycloheptenyl, cycloheptyl, cycloheptenyl, adamantyl, cyclooctyl, cyclooctenyl, cyclooctadienyl, fluorenyl, phenyl, naphthyl, indanyl, adamantyl and tetrahydronaphthyl. Bridged rings are also included in the definition of carbocycle, including, for example, [3.3.0]bicyclooctane, [4.3.0]bicyclononane, [4.4.0]bicyclodecane and [2.2.2]bicyclooctane. A bridged ring occurs when one or more carbon atoms link two non-adjacent carbon atoms. In one embodiment, bridge rings are one or two carbon atoms. It is noted that a bridge always converts a monocyclic ring into a tricyclic ring. When a ring is bridged, the substituents recited for the ring may also be present on the bridge. Fused (e.g., naphthyl, tetrahydronaphthyl) and spiro rings are also included.

As used herein, “heterocycle” includes any ring structure (saturated or partially unsaturated) which contains at least one ring heteroatom (e.g., N, O or S). Examples of heterocycles include, but are not limited to, morpholine, pyrrolidine, tetrahydrothiophene, piperidine, piperazine and tetrahydrofuran.

Examples of heterocyclic groups include, but are not limited to, acridinyl, azocinyl, benzimidazolyl, benzofuranyl, benzothiofuranyl, benzothiophenyl, benzoxazolyl, benzoxazolinyl, benzthiazolyl, benztriazolyl, benztetrazolyl, benzisoxazolyl, benzisothiazolyl, benzimidazolinyl, carbazolyl, 4aH-carbazolyl, carbolinyl, chromanyl, chromenyl, cinnolinyl, decahydroquinolinyl, 2H,6H-1,5,2-dithiazinyl, dihydrofuro[2,3-b]tetrahydrofuran, furanyl, furazanyl, imidazolidinyl, imidazolinyl, imidazolyl, 1H-indazolyl, indolenyl, indolinyl, indolizinyl, indolyl, 3H-indolyl, isatinoyl, isobenzofuranyl, isochromanyl, isoindazolyl, isoindolinyl, isoindolyl, isoquinolinyl, isothiazolyl, isoxazolyl, methylenedioxyphenyl, morpholinyl, naphthyridinyl, octahydroisoquinolinyl, oxadiazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl, 1,2,5-oxadiazolyl, 1,3,4-oxadiazolyl, 1,2,4-oxadiazol5(4H)-one, oxazolidinyl, oxazolyl, oxindolyl, pyrimidinyl, phenanthridinyl, phenanthrolinyl, phenazinyl, phenothiazinyl, phenoxathinyl, phenoxazinyl, phthalazinyl, piperazinyl, piperidinyl, piperidonyl, 4-piperidonyl, piperonyl, pteridinyl, purinyl, pyranyl, pyrazinyl, pyrazolidinyl, pyrazolinyl, pyrazolyl, pyridazinyl, pyridooxazole, pyridoimidazole, pyridothiazole, pyridinyl, pyridyl, pyrimidinyl, pyrrolidinyl, pyrrolinyl, 2H-pyrrolyl, pyrrolyl, quinazolinyl, quinolinyl, 4H-quinolizinyl, quinoxalinyl, quinuclidinyl, tetrahydrofuranyl, tetrahydroisoquinolinyl, tetrahydroquinolinyl, tetrazolyl, 6H-1,2,5-thiadiazinyl, 1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl, 1,3,4-thiadiazolyl, thianthrenyl, thiazolyl, thienyl, thienothiazolyl, thienooxazolyl, thienoimidazolyl, thiophenyl, triazinyl, 1,2,3-triazolyl, 1,2,4-triazolyl, 1,2,5-triazolyl, 1,3,4-triazolyl and xanthenyl.

The term “substituted”, as used herein, means that any one or more hydrogen atoms on the designated atom is replaced with a selection from the indicated groups, provided that the designated atom's normal valency is not exceeded, and that the substitution results in a stable compound. When a substituent is keto (i.e., ═O), then 2 hydrogen atoms on the atom are replaced. Keto substituents are not present on aromatic moieties. Ring double bonds, as used herein, are double bonds that are formed between two adjacent ring atoms (e.g., C═C, C═N or N═N). “Stable compound” and “stable structure” are meant to indicate a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture, and formulation into an efficacious therapeutic agent.

As used herein, a “subject in need thereof” is a subject having a neurological disease. In one embodiment, a subject in need thereof has multiple sclerosis. A “subject” includes a mammal. The mammal can be e.g., any mammal, e.g., a human, primate, bird, mouse, rat, fowl, dog, cat, cow, horse, goat, camel, sheep or a pig. In one embodiment, the mammal is a human.

The present invention provides methods for the synthesis of the compounds of each of the formulae described herein. The present invention also provides detailed methods for the synthesis of various disclosed compounds of the present invention according to the following schemes and as shown in the Examples.

Throughout the description, where compositions are described as having, including, or comprising specific components, it is contemplated that compositions also consist essentially of, or consist of, the recited components. Similarly, where methods or processes are described as having, including, or comprising specific process steps, the processes also consist essentially of, or consist of, the recited processing steps. Further, it should be understood that the order of steps or order for performing certain actions is immaterial so long as the invention remains operable. Moreover, two or more steps or actions can be conducted simultaneously.

The synthetic processes of the invention can tolerate a wide variety of functional groups; therefore various substituted starting materials can be used. The processes generally provide the desired final compound at or near the end of the overall process, although it may be desirable in certain instances to further convert the compound to a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof.

Compounds of the present invention can be prepared in a variety of ways using commercially available starting materials, compounds known in the literature, or from readily prepared intermediates, by employing standard synthetic methods and procedures either known to those skilled in the art, or which will be apparent to the skilled artisan in light of the teachings herein. Standard synthetic methods and procedures for the preparation of organic molecules and functional group transformations and manipulations can be obtained from the relevant scientific literature or from standard textbooks in the field. Although not limited to any one or several sources, classic texts such as Smith, M. B., March, J., March's Advanced Organic Chemistry Reactions, Mechanisms, and Structure, 5^(th) edition, John Wiley & Sons: New York, 2001; and Greene, T. W., Wuts, P. G. M., Protective Groups in Organic Synthesis, 3^(rd) edition, John Wiley & Sons: New York, 1999, incorporated by reference herein, are useful and recognized reference textbooks of organic synthesis known to those in the art. The following descriptions of synthetic methods are designed to illustrate, but not to limit, general procedures for the preparation of compounds of the present invention.

Compounds of the present invention can be conveniently prepared by a variety of methods familiar to those skilled in the art. The compounds of this invention with each of the formulae described herein may be prepared according to the following procedures from commercially available starting materials or starting materials which can be prepared using literature procedures. These procedures show the preparation of representative compounds of this invention.

General Procedure 1

To a mixture of monomethyl fumarate (MMF) (1.0 equivalent) and HBTU (1.5 equivalents) in DMF (25 ml per g of MMF) was added Hunigs base (2.0 equivalents). The dark brown solution was stirred for 10 minutes, where turned into a brown suspension, before addition of the alcohol (1.0-1.5 equivalents). The reaction was stirred for 18 hours at room temperature. Water was added and the product extracted into ethyl acetate three times. The combined organic layers were washed with water three times, dried with magnesium sulphate, filtered and concentrated in vacuo at 45° C. to give the crude product. The crude product was purified by silica chromatography and in some cases further purified by trituration with diethyl ether to give the clean desired ester product. All alcohols were either commercially available or made following known literature procedures.

General Procedure 2—Conversion of the Ester Product into the Hydrochloride Salt

To a mixture of the ester product in diethyl ether (25 ml per g) was added 2M HCl in diethyl ether (1.5 equivalents). The mixture was stirred at room temperature for two hours. The solvent was decanted, more diethyl ether added and the solvent decanted again. The remaining mixture was then concentrated in vacuo at 45° C. and further dried in a vacuum oven at 55° C. for 18 hours to give the solid HCl salt.

General Procedure 3

To a 100 mL, one-necked, round-bottomed flask, fitted with a magnetic stirrer and nitrogen inlet/outlet, were added 11 mL of an MTBE solution containing freshly prepared mono-methyl fumaryl chloride (4.9 g, 33 mmol) and 50 mL of additional MTBE at 20° C. The resulting yellow solution was cooled to <20° C. with an ice water bath. Then, the alcohol, (33 mmol, 1 eq) was added dropwise, via syringe, over approximately 10 minutes. The reaction mixture was allowed to stir at <20° C. for 10 minutes after which time the cooling bath was removed and the reaction was allowed to warm to 20° C. and stir at 20° C. temperature for 16 hours. The reaction was deemed complete by TLC after 16 hours at RT. The reaction mixture was filtered through a medium glass fritted funnel to collect the off-white solids. The solids were dried in a vacuum oven at 25° C. overnight to afford the final product as an HCl salt. All alcohols were either commercially available or made following known literature procedures.

Chemical Analysis/Procedures

The NMR spectra described herein were obtained with a Varian 400 MHz NMR spectrometer using standard techniques known in the art.

EXAMPLES Example 1 (E)-2,2′-((2-((4-methoxy-4-oxobut-2-enoyl)oxy)ethyl)azanediyl)diacetic acid hydrochloride (1)

To a solution of 2-(bis(2-(tert-butoxy)-2-oxoethyl)amino)ethyl methyl fumarate (2.52 g, 6.2 mmol) in dioxane (25 ml) was added 2M HCl in dioxane (30 ml) and the mixture stirred for 90 hours. The precipitate was filtered, washed with diethyl ether and dried in a vacuum oven at 55° C. for 18 hours to give (E)-2,2′-((2-(4-methoxy-4-oxobut-2-enoyl)oxy)ethyl)azanediyl)diacetic acid hydrochloride, a white solid (1.31 g, 65%).

¹H NMR (300 MHz, MeOD): δ 6.87 (2H, dd, J=16.1 Hz); 4.46-4.53 (2H, m); 4.09 (4H, s); 3.79 (3H, s); 3.57-3.63 (2H, m). [M+H]⁺=290.12.

Methyl (2-(methyl(2-(methylsulfonyl)ethyl)amino)ethyl) fumarate hydrochloride (2)

Methyl (2-(N-methylmethylsulfonamido)ethyl) fumarate 2 was synthesized following general procedure 1 and was converted to the HCl salt methyl (2-(methyl(2-(methylsulfonyl)ethyl)amino)ethyl) fumarate hydrochloride (procedure 2) (1.39 g, 95%).

¹H NMR (400 MHz, DMSO): δ 11.51 (1H, m); 6.83 (2H, dd, J=15.8 Hz); 4.48 (1H, bs); 3.24-3.90 (7H, m); 3.07 (3H, s); 2.78 (2H, bs). [M+H]⁺=294.09.

2-(dimethylamino)propyl methyl fumarate hydrochloride (3)

2-(dimethylamino)propyl methyl fumarate 3 was synthesized following general procedure 1 and was converted to the HCl salt: 2-(dimethylamino)propyl methyl fumarate hydrochloride (procedure 2) (329 mg, 92%).

1H NMR (300 MHz, DMSO): δ 10.40 (1H, bs); 6.86 (2H, dd, J=15.8 Hz); 4.25-4.46 (2H, m); 3.71 (3H, s); 3.34 (1H, s); 2.69 (6H, s); 1.24 (3H, s). [M+H]⁺=216.14.

(E)-2-(4-methoxy-4-oxobut-2-enoyl)oxy)-N,N,N-trimethylethanaminium iodide (4)

To a solution of 2-(dimethylamino)ethyl methyl fumarate 19 (760 mg, 3.7 mmol) in diethyl ether (20 ml) was added methyl iodide (246 μl, 3.9 mmol). The mixture was stirred at room temperature for 18 hours where a precipitate slowly formed. The mixture was filtered, washed with diethyl ether and dried in a vacuum oven at 55° C. for 18 hours to give (E)-2-((4-methoxy-4-oxobut-2-enoyl)oxy)-N,N,N-trimethylethanaminium iodide, a white solid (1.15 g, 90%).

1H NMR (300 MHz, DMSO): δ 6.80 (2H, dd, J=16.1 Hz); 4.56 (2H, bs); 3.66-3.75 (5H, m); 3.11 (9H, s). [M+H]⁺=216.14.

2-(4,4-difluoropiperidin-1-yl)ethyl methyl fumarate hydrochloride (5)

2-(4,4-difluoropiperidin-1-yl)ethyl methyl fumarate 5 was synthesized following general procedure 1 and was converted to the HCl salt: 2-(4,4-difluoropiperidin-1-yl)ethyl methyl fumarate hydrochloride (procedure 2) (780 mg, 87%).

¹H NMR (300 MHz, DMSO): δ 11.25 (1H, bs); 6.84 (2H, dd, J=16.1 Hz); 4.50 (2H, bs); 3.35-4.00 (8H, m); 3.05-3.30 (2H, m); 2.20-2.45 (3H, s). [M+H]⁺=278.16.

1-(dimethylamino)propan-2-yl methyl fumarate hydrochloride (6)

1-(dimethylamino)propan-2-yl methyl fumarate 6 was synthesized following general procedure 1 and was converted to the HCl salt 1-(dimethylamino)propan-2-yl methyl fumarate hydrochloride (procedure 2) (690 mg, 72%).

¹H NMR (300 MHz, DMSO): δ 10.41 (1H, bs); 6.80 (2H, dd, J=15.8 Hz); 5.18-5.33 (1H, m); 3.20-3.55 (2H, m); 3.72 (3H, s); 2.60-2.80 (7H, m); 1.18-1.28 (3H, m). [M+H]⁺=216.14.

Methyl (2-thiomorpholinoethyl) fumarate hydrochloride (7)

Methyl (2-thiomorpholinoethyl) fumarate 7 was synthesized following general procedure 1 and was converted to the HCl salt, methyl (2-thiomorpholinoethyl) fumarate hydrochloride (procedure 2) (623 mg, 93%).

¹H NMR (300 MHz, DMSO): δ 11.03 (1H, bs); 6.83 (2H, dd, J=15.6 Hz); 4.50 (2H, s); 3.00-3.80 (11H, m); 2.70-2.80 (2H, m). [M+H]⁺=216.14. [M+H]⁺=260.11.

Methyl (2-(phenylamino)ethyl) fumarate hydrochloride (8)

Methyl (2-(phenylamino)ethyl) fumarate 8 was synthesized following general procedure 1 and was converted to the HCl salt methyl (2-(phenylamino)ethyl) fumarate hydrochloride (procedure 2) (1.80 g, quantitative).

¹H NMR (300 MHz, DMSO): δ 6.50-6.80 (9H, m); 4.29 (2H, t, 4.4 Hz); 3.72 (3H, s); 3.45 (2H, t, J=4.5 Hz). [M+H]⁺=250.13.

2-(dimethylamino)-2-methylpropyl methyl fumarate hydrochloride (9)

2-(dimethylamino)-2-methylpropyl methyl fumarate 9 was synthesized following general procedure 1 and was converted to the HCl salt, 2-(dimethylamino)-2-methylpropyl methyl fumarate hydrochloride (procedure 2) (883 mg, 76%).

¹H NMR (300 MHz, DMSO): δ 10.20 (1H, bs); 6.91 (2H, dd, J=15.6 Hz); 4.29 (2H, s); 3.73 (3H, s); 2.57-2.80 (6H, m); 1.32 (6H, s). [M+H]⁺=230.16.

Methyl (2-(methylsulfonyl)ethyl) fumarate (10)

Methyl (2-(methylsulfonyl)ethyl) fumarate 10 was synthesized following general procedure 1 and (1.01 g, 37%).

¹H NMR (400 MHz, CDCl₃): δ 6.88 (2H, dd, J=16.0 Hz); 4.66 (2H, t, J=5.8 Hz); 3.82 (3H, s); 3.38 (2H, t, J=6.0 Hz); 2.99 (3H, s). [M+H]⁺=236.97.

2-(1,1-dioxidothiomorpholino)ethyl methyl fumarate hydrochloride (11)

2-(1,1-dioxidothiomorpholino)ethyl methyl fumarate 11 was synthesized following general procedure 1 and was converted to the HCl salt 2-(1,1-dioxidothiomorpholino)ethyl methyl fumarate hydrochloride (procedure 2) (1.33 g, 87%).

¹H NMR (400 MHz, DMSO): δ 6.79 (2H, dd, J=15.8 Hz); 4.34 (2H, bs); 3.72 (4H, s); 2.90-3.70 (11H, m). [M+H]⁺=292.11.

Methyl (2-(methyl(phenyl)amino)ethyl) fumarate hydrochloride (12)

Methyl (2-(methyl(phenyl)amino)ethyl) fumarate 12 was synthesized following general procedure 1 and was converted to the HCl salt methyl (2-(methyl(phenyl)amino)ethyl) fumarate hydrochloride (procedure 2) (1.76 g, 97%).

¹H NMR (400 MHz, DMSO): δ 6.72-7.40 (5H, m); 6.64 (2H, dd, J=16.0 Hz); 4.27 (2H, s); 3.70 (5H, s); 2.97 (3H, s). [M+H]⁺=264.14.

2-(benzyl(methyl)amino)ethyl methyl fumarate hydrochloride (13)

2-(benzyl(methyl)amino)ethyl methyl fumarate 13 was synthesized following general procedure 1 and was converted to the HCl salt 2-(benzyl(methyl)amino)ethyl methyl fumarate hydrochloride (procedure 2) (2.70 g, 96%).

¹H NMR (400 MHz, DMSO): δ 10.65 (1H, bs); 7.39-7.60 (5H, m); 6.82 (2H, dd, J=15.8 Hz); 4.20-4.60 (4H, m); 3.73 (3H, s); 3.27-3.50 (2H, m); 2.69 (3H, s). [M+H]⁺=278.16.

2-(2,5-dioxopyrrolidin-1-yl)ethyl methyl fumarate (14)

2-(2,5-dioxopyrrolidin-1-yl)ethyl methyl fumarate 14 was synthesized following general procedure 1 (1.03 g, 35%).

¹H NMR (400 MHz, DMSO): δ 6.81 (2H, dd, J=15.8 Hz); 4.36 (2H, t, J=5.3 Hz); 3.84 (2H, t, J=5.1 Hz); 3.80 (3H, s); 2.73 (4H, s). [M+H]⁺=256.07.

Methyl (2-(piperidin-1-yl)ethyl) fumarate hydrochloride (15)

Methyl (2-(piperidin-1-yl)ethyl) fumaratehydrochloride 15 was synthesized following general procedure 3.

¹H NMR (400 MHz, DMSO-d6) δ 10.76 (s, 1H), 6.94-6.77 (m, 2H), 4.58-4.51 (m, 2H), 3.76 (s, 3H), 3.48-3.36 (m, 4H), 2.94 (dddd, J=15.9, 12.1, 9.2, 4.4 Hz, 2H), 1.91-1.64 (m, 5H), 1.37 (dtt, J=16.4, 11.3, 4.9 Hz, 1H). [M+H]⁺=241.93.

Methyl (2-morpholinoethyl) fumarate hydrochloride (16)

Methyl (2-morpholinoethyl) fumaratehydrochloride 16 was synthesized following general procedure 3.

¹H 1H NMR (400 MHz, DMSO-d6) δ 11.36 (s, 1H), 6.92 (d, J=15.9 Hz, 1H), 6.82 (d, J=15.9 Hz, 1H), 4.60-4.52 (m, 2H), 4.00-3.77 (m, 6H), 3.76 (s, 3H), 3.22-3.04 (m, 4H). [M+H]⁺=244.00.

2-(1,4-dioxa-8-azaspiro[4.5]decan-8-yl)ethyl methyl fumarate hydrochloride (17)

2-(1,4-dioxa-8-azaspiro[4.5]decan-8-yl)ethyl methyl fumarate hydrochloride 17 was synthesized following general procedure 3.

¹H NMR (400 MHz, DMSO-d6) δ 11.26 (s, 1H), 6.91 (d, J=15.9 Hz, 1H), 6.82 (d, J=15.9 Hz, 1H), 4.58-4.51 (m, 2H), 3.93 (s, 4H), 3.76 (s, 3H), 3.57-3.43 (m, 4H), 3.22-3.03 (m, 2H), 2.20-2.02 (m, 2H), 1.89-1.79 (m, 2H). [M+H]⁺=300.00.

Methyl (2-(pyrrolidin-1-yl)ethyl) fumarate hydrochloride (18)

Methyl (2-(pyrrolidin-1-yl)ethyl) fumarate hydrochloride 18 was synthesized following general procedure 3.

¹H NMR (400 MHz, DMSO-d6) δ 11.12 (s, 1H), 6.94 (d, J=15.8 Hz, 1H), 6.82 (d, J=15.8 Hz, 1H), 4.53-4.46 (m, 2H), 3.76 (s, 3H), 3.61-3.45 (m, 4H), 3.11-2.94 (m, 2H), 2.06-1.79 (m, 4H). [M+H]⁺=228.46.

2-(dimethylamino)ethyl methyl fumarate hydrochloride (19)

2-(dimethylamino)ethyl methyl fumarate hydrochloride 19 was synthesized following general procedure 3.

¹H NMR (500 MHz, DMSO-d6) δ 10.87 (s, 1H), 6.93 (d, J=15.9 Hz, 1H), 6.80 (d, J=15.9 Hz, 1H), 4.53-4.45 (m, 2H), 3.75 (s, 3H), 3.44-3.38 (m, 2H), 2.77 (s, 5H). [M+H]⁺=201.84.

2-(diethylamino)ethyl methyl fumarate hydrochloride (20)

2-(diethylamino)ethyl methyl fumarate hydrochloride 20 was synthesized following general procedure 3.

¹H NMR (400 MHz, DMSO-d6) δ 10.85 (s, 1H), 6.90 (d, J=15.8 Hz, 1H), 6.81 (d, J=15.9 Hz, 1H), 4.56-4.48 (m, 2H), 3.76 (s, 3H), 3.48-3.38 (m, 2H), 3.15 (qq, J=9.7, 5.5, 4.9 Hz, 4H), 1.24 (t, J=7.3 Hz, 6H). [M+H]⁺=230.59.

Reference Compound A 2-(diethylamino)-2-oxoethyl methyl fumarate

2-(diethylamino)-2-oxoethyl methyl fumarate was synthesized following general procedure 3 and conformed to reported data in U.S. Pat. No. 8,148,414.

Example 2 Aqueous Chemical Stability of Several Compounds

Stock solutions of the compounds in acetonitrile or acetonitrile/methanol were prepared at 20 mg/mL. and 20 μL, spiked into 3 mL of buffer phosphate (100 mM) and incubated at 37° C. Aliquots (50 μL) were sampled at different time points and diluted 20 fold with ammonium formate (pH 3.5)/acetonitrile. The diluted samples were analyzed by HPLC. The peak areas corresponding to the compounds were plotted against time and the data were fitted to a first-order mono-exponential decay where the rate constant and the half-life were determined (Table 2). In some cases, in which the half-life is too long (>360 min), an estimated value of the half-life is reported using the initial slope at low conversion (<10%).

TABLE 2 Compound pH 8 (t ½, min) 6 2.0 7 26.0 8 36.0 9 7.0 10 67.0 11 >240 12 396 14 144 15 3.0 16 20.0 17 11.0 18 5.0 19 6.0 20 5.0 Reference 120 Compound A

Example 3 Evaluation of Aqueous Chemical Stability with NMR

The chemical hydrolysis was followed by dissolving the ester in phosphate buffered D₂O (pH 7.9) in an NMR tube, heating the NMR tube to 37° C. and periodically recording the spectra. These various species produced by hydrolysis of the diesters were followed over time. See FIGS. 1-5.

While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims. 

1. A compound of Formula (I), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof:

wherein: R₁ is unsubstituted C₁-C₆ alkyl; L_(a) is substituted or unsubstituted C₁-C₆ alkyl linker, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S; and R₂ and R₃ are each, independently, H, substituted or unsubstituted C₁-C₆ alkyl, substituted or unsubstituted C₂-C₆ alkenyl, substituted or unsubstituted C₂-C₆ alkynyl, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S; or alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S or a substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.
 2. The compound of claim 1, wherein R₁ is methyl.
 3. The compound according to claim 1, wherein L_(a) is substituted or unsubstituted C₁-C₆ alkyl linker.
 4. The compound according to claim 1, wherein R₂ is substituted or unsubstituted C₁-C₆ alkyl and R₃ is H.
 5. The compound according to claim 1, wherein R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S or a substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.
 6. A compound of Formula (Ia), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof:

wherein: R₁ is unsubstituted C₁-C₆ alkyl; L_(a) is substituted or unsubstituted C₁-C₆ alkyl linker, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S; and R₂ is H, substituted or unsubstituted C₁-C₆ alkyl, substituted or unsubstituted C₂-C₆ alkenyl, substituted or unsubstituted C₂-C₆ alkynyl, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.
 7. A compound of Formula (Ib), or a pharmaceutically acceptable polymorph, hydrate, solvate or co-crystal thereof:

A⁻ is a pharmaceutically acceptable anion; R₁ is unsubstituted C₁-C₆ alkyl; L_(a) is substituted or unsubstituted C₁-C₆ alkyl linker, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S; R₃′ is substituted or unsubstituted C₁-C₆ alkyl; and R₂ and R₃ are each, independently, H, substituted or unsubstituted C₁-C₆ alkyl, substituted or unsubstituted C₂-C₆ alkenyl, substituted or unsubstituted C₂-C₆ alkynyl, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S; or alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached, form a substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or a substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.
 8. A compound of Formula (II), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof:

wherein: R₁ is unsubstituted C₁-C₆ alkyl; R₄ and R₅ are each, independently, H, substituted or unsubstituted C₁-C₆ alkyl, substituted or unsubstituted C₂-C₆ alkenyl, substituted or unsubstituted C₂-C₆ alkynyl, substituted or unsubstituted C₆-C₁₀ aryl, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S; R₆, R₇, R₈ and R₉ are each, independently, H, substituted or unsubstituted C₁-C₆ alkyl, substituted or unsubstituted C₂-C₆ alkenyl, substituted or unsubstituted C₂-C₆ alkynyl or C(O)OR_(a); and R_(a) is H or substituted or unsubstituted C₁-C₆ alkyl.
 9. A compound of Formula (III), or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof:

wherein: R₁ is unsubstituted C₁-C₆ alkyl;

is selected from the group consisting of:

X is N, O, S or SO₂; Z is C or N; m is 0, 1, 2, or 3; n is 1 or 2; w is 0, 1, 2 or 3; t is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10; R₆, R₇, R₈ and R₉ are each, independently, H, substituted or unsubstituted C₁-C₆ alkyl, substituted or unsubstituted C₂-C₆ alkenyl, substituted or unsubstituted C₂-C₆ alkynyl or C(O)OR_(a); and R_(a) is H or substituted or unsubstituted C₁-C₆ alkyl; and each R₁₀ is, independently, H, halogen, substituted or unsubstituted C₁-C₆ alkyl, substituted or unsubstituted C₂-C₆ alkenyl, substituted or unsubstituted C₂-C₆ alkynyl, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S; or, alternatively, two R₁₀'s attached to the same carbon atom, together with the carbon atom to which they are attached, form a carbonyl, substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S; or, alternatively, two R₁₀'s attached to different atoms, together with the atoms to which they are attached, form a substituted or unsubstituted C₃-C₁₀ carbocycle, substituted or unsubstituted heterocycle comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S, or substituted or unsubstituted heteroaryl comprising one or two 5- or 6-member rings and 1-4 heteroatoms selected from N, O and S.
 10. A method of treating a neurological disease by administering to a subject in need thereof a therapeutically effective amount of a compound according to claim 1 or a pharmaceutically acceptable salt, polymorph, hydrate, solvate or co-crystal thereof.
 11. The method of claim 10, wherein the neurological disease is multiple sclerosis.
 12. The method of claim 10, wherein the neurological disease is relapsing-remitting multiple sclerosis.
 13. The method of claim 1, wherein the compound of formula (I) is a pharmaceutically acceptable salt.
 14. A pharmaceutical composition comprising: (i) a therapeutically effective amount of a compound of claim 1; and (ii) a pharmaceutically acceptable carrier or excipient.
 15. The composition of claim 14, wherein the therapeutically effective amount is sufficient for the treatment of multiple sclerosis.
 16. (canceled) 